Comp won't standby -> driver or prog won't allow it

[cdrsft]

On my Win98 PC, which used to standby without any problems, now gives the following error when asked to standby;

"Windows cannot go into Standby mode because a program or device driver won't allow it".

I have tried;
a) Stopping all programs and system services (same result)
b) Cleaning the registry of ALL startup programs and services (same result)
c) Reinstalling Win9x over top to replace system files (same result)

I am getting real frustrated, and I want to avoid a format/reinstall at *all* costs.

Any suggestions? No changes have been made in BIOS, the only things that have changed are programs being added.

Thanks in advance